ABSTRACT
Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114 Nature of Tropical Grasslands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115 Origin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116
Successional Levels. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116 Diverse Grassland Communities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118
Biodiversity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118 Species Diversity in the World . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119
Community Diversity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120 Ecosystem Diversity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121
Structure of Tropical Grassland . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121 Abiotic Characteristics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123 Biotic Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123 Production Strategy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124 Primary Productivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125 Secondary Productivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126
Biological Interactions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126 Biophysical Interactions at the Ecosystem Level: Exploratory
Studies at Iseilema Grasslands of Ujjain, India . . . . . . . . . . . . . . . 127 Interspecific and Intraspecific Interactions. . . . . . . . . . . . . . . . . . . . . 131 Biophysical Interactions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131 Interaction of Trees and Grasses. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133 Aboveground Interactions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133 Belowground Interactions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134
Grass-Legume Interactions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135 Trees-Grass-Livestock Interactions . . . . . . . . . . . . . . . . . . . . . . . . . . . 135 Tree/Grass-Legume-Animal Interactions. . . . . . . . . . . . . . . . . . . . . . 136
Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139
INTRODUCTION
The grassland biome is characterized by grasses and their relatives where the dominant life forms are mixed with herbaceous plants. Grassland ecosystems consist of many interacting environmental forces, local combinations of organisms, and the impacts of use by an increasing number of people. These systems remain primarily under the control of overall environment, although use and management of grassland ecosystems alter populations of organisms, change the rate of physical and biological inputs, and account for about 25% of earth’s natural vegetation. Grassland ecosystem components include soil, vegetation, populations, communities, and animals. Most of the extensive areas of existing natural grassland have undergone changes through man-tree-grass-animal interactions. Significant impact from grazing and fire has been noticed. Plants are often adapted to fast, scattered fires that burn the tops of plants but leave seeds, roots, or other resistant structures intact. Examples include the tall grass prairie of the U.S. and Canada, the steppes of Central Asia, and the plains of Africa. Because these areas are often suitable for cultivation or livestock grazing, a great deal of this biome around the world has been highly modified, often for many centuries or millennia.
